John Adams is one of the most popular of contemporary composers, but this should hardly come as a surprise, as his work is vibrant, propulsive, exuberant and muscular. Unlike his Minimalist forebears -- Terry Riley, La Monte Young, Steve Reich -- Adams is loathe to work only within the confines of a system marked by its static nature, relying as it does upon repetition. The composer is a self-described "post-Minimalist," as much of his work utilizes the hypnotic, circular and (of course) repetitive rhythms found in the genre. However, it also displays ample variety in terms of sweeping dynamic shifts, changes in tonality and a willingness to indulge in decidedly dramatic developments. This is evident in his wonderful 1985 work Harmonielehre, in which the opening chords crash upon the listener with all the impact of an 18-wheeler being driven through a wall, leaving you with the same breathless feeling a Beethoven symphony can produce. The rush provided by the first movement is contrasted with the more subdued, lush and almost neo-Romantic second movement. In the third and final section, Adams allows for more than one tonal center, creating a kind of struggle that pushes the music forward with unshakeable vigor.